In silent mode, the Installer operates from a predefined answer file representing your responses to the GUI screens. This allows you to script the installation process in advance and then perform it in batch mode without actually displaying the GUI screens and responding to them interactively.
To create an answer file, start the Installer with the -n option:
$ installer -n answerFile
where answerFile identifies the file in which to record your responses. This causes the Installer to execute a “dry run,” presenting the sequence of GUI screens without actually performing the installation. Your input responses are recorded in the specified answer file. You can then perform the installation at a later time by starting the Installer with the -s (“silent”) option, specifying the same answer file:
$ installer -s -a answerFile
This performs a silent installation as defined by the answer file, without visibly displaying the GUI screens.